React: Refs

• Gives access to a single DOM element
• Create refs in the constructor, assign them to instance variables, then pass to a particular JSX elements as props.

Redux: Thunk

What's a thunk?

Thunk廣泛指的是: 延後執行的wrapper。

// calculation of 1 + 2 is immediate
// x === 3
let x = 1 + 2;

// calculation of 1 + 2 is delayed
// foo can be called later to perform the calculation
// foo is a thunk!
let foo = () => 1 + 2;

Thunk in Redux:

在Redux中的Thunk應用則是指"延後執行Dispatch"。

Thunk middleware 會幫助dispatch async action, 等待action 執行完畢後再 dispatch 內容至store，達到非同步。

這個dispatch 的內容並非帶值的 action，而是一個async function，執行完畢前皆未有值；執行完畢後，此async function 將另外寫一個dispatch，自行再次dispatch至store (這次的dispatch就如同一般的同步disptch function一樣)。